considering the fallout (3 and new vegas) dlc which is always $10 is often just as long if not longer in some cases than many shooters out there some which go for $60 i think that's a highly weak agrument. this is additional content clearly as most of them, all of new vegas so far, don't even take place in the main game world. even the crappiest fallout dlcs, mothership zeta, and operation anchorage were at least worth $5 and some of the better ones were probably worth over $15 to me.
after just playing Minerva's Den for Bioshock 2 that was far and above worth the $10. a different story, new content, different writing, tons of hours by many hands taken as an after effect to the main game. dlc is only nickel and dimed when it is usual cheap crap like most bioware, and when its adding onto a game that may not merit from new designs as much as a full on 3rd/1st person world that can trully off a "new" gaming experience worth an extra price. i see dlcs as no more aggregious than sequels in the first place that don't merit them. i'd rather have devs save money rather than focusing on a beefed up engine and simply beef up the things that cost much less money.